The runtime-cache directory caches information used by subuser while prepairing subusers to be run.

The directory contains a set of subdirectories each named with the Docker image Id of a given installed-image.

Each image directory contains a set of JSON files named with the SHA512 hash of the permissions.json file that was used to generate the runtime and postfixed with .json.

In summary, the path to a given runtime config might look like $HOME/.subuser/runtime-cache/<Docker-image-Id>/<permissions-hash>.json.

Each permissions-specific JSON file caches information needed to run a specific installed subuser image with a specific set of permissions. Each permissions specific JSON file is a valid JSON file containing a single JSON object with the following properites:

run-ready-image-id - the Docker image Id of the image which was prepaired for running that subuser.